Preparation of the Calibration Baseline for Sentinel-2 Collection 1

The Sentinel-2 mission observes the Earth in 13 spectral bands in the visible and SWIR with a repeat cycle of 5 days for each satellite unit A and B. A complete reprocessing of the Sentinel-2 archive to generate the "Collection-1" is currently under preparation. In this presentation we describe the activities performed by the Sentinel-2 Mission Performance Center to prepare the calibration baseline for Collection-1. The preparation activities involve a correction of some minor errors in the definition of the spectral response function at the beginning of the mission. A more significant change concerns the possible harmonization between the two sensors. Indeed, radiometric validation results reported by different teams confirm the presence of a small bias (around 1%) in the visible range between the satellites. Sentinel-2B is generally believed to be slightly too dark, while Sentinel-2A agrees better with other references. The presentation will describe the inter-satellite bias assessment as well as a study of the impact of a potential harmonization on Level-2 products.